Testing an Electrical Water Temp Gauge With External Power

[JPC1972]

Has anyone tested an electric water temp gauge with an external power source other than a 12V battery? I am trying to test mine using a 110to12Volt converter and I hooked it all up according to the instructions but the needle just drops to the bottom and doesn move even though the watter is boiling. I have tried two senders and it does the same thing. The 110volt converter is 1amp. Any ideas? I am wondering if the sender needs to be grounded at the threads that would normally be screwed into the engine.

[basshound71]

I don't know about testing with external power. I know on a fuel gauge you take the wire off of the sending unit and ground it out. If the gauge moves the gauge is good and the sender is bad. I believe the temp gauge is the same

[Kurt Combs]

The sender grounds through the threads. I don't know why we call them senders, they are really variable switches that lead to ground. Try grounding the wire and see if the gauge moves. Is your oil pressure also low? There is an adjustment on the back of the gauge panel that I believe has an impact on both of those gauges. You might try doing a search on this site to see if there is already a thread on the topic. I know I adjusted mine years ago and it helped. If my memory is correct (and it may not be) both of the gauges will go up or down together when you adjust it. I am assuming you don't have idiot lights.

[JPC1972]

Basshound71 and Kurt Combs Thanks for responding.. I should have explained this is an aftermarket electrical temp gauge from equus.. not the stock panel. I am trying to test this gauge with the oem temp sender to see if it will work. If I ground the threads of the sender can i just ground it to the ground wire from the converter? I will post some pics to show what I am trying to do .. here is a link to the manual for installing .. I am trying to do this outside the truck with eternal power .. the diagram I am looking at is the electrical water temp gauge http://iequus.com/Content/Support/Manua ... 1.revB.pdf

[Kurt Combs]

Oooooohhh, that is different.

[knightfire83]

This will work to test it. The Equus gauge probably uses a different ohms range than the factory sender though.